1. Field of the Invention
The present invention relates to a novel thixotropic agent.
2. State of the Art
It is desirable that some kinds of compositions used in the form of a highly viscous liquid or a paste such as paints, sealing material or caulking material generally called "patching compound" and adhesives have fluidity or plasticity higher at the time of being applied, but lower after the application.
Such a characteristic can be realized by providing a thixotropic property to the compositions, i.e., the property of exhibiting a high fluidity during deformation by force of a sprayer, roller or trowel, but losing the fluidity when left at rest.
Hitherto, as a thixotropic agent, fine powder silica has a wide range of use. It is, however, expensive. Bentonite and starch are also used. As far as performance is concerned, asbestos is an excellent thixotropic agent, and particularly, specially treated asbestos has been used by preference because of its remarkable effect. However, as the objectionable influences of asbestos on human health became clear, use of asbestos has been put under control which is getting more strict.
German Patent Disclosure No. 2,426,188 describes use of short polyolefin fibers and fibers having a high fibrillation level as a thickening agent for aqueous painting, coating and layering materials.
There has been a great demand for a thixotropic agent which is useful for not only aqueous materials but also oily or organic material, e.g., polyester resin, and further, which is applicable for use with a spray gun without any trouble such as plugging of spray nozzles.